Solid surface modification method and apparatus

Abstract

A liquid compound or a compound solution is kept in contact with the surface of a solid material, such as a synthetic resin, glass, metal, or ceramic, radiation selected from ultraviolet radiation, visible radiation, and infrared radiation is irradiated on the interface between the surface of the solid material and the liquid compound or compound solution to optically excite the surface of the solid material and the liquid compound or compound solution, thereby effecting substitution with a chemical species in the liquid compound or compound solution, depositing the chemical species, or performing etching with the chemical species. Preferably, a transparent window is kept in tight contact with the surface of a solid material to be treated, a thin layer of a liquid compound or of a compound solution is interposed between the surface of the solid material and the transparent window by using capillarity, and ultraviolet radiation, visible radiation, or infrared radiation is irradiated through the transparent window. With this treatment, the irradiated portion can be imparted with hydrophilicity, adhesion properties printing properties, a corrosion resistance, and conductivity.

Description

The present invention relates to a method of photochemically modifying the surface of a solid workpiece to be surface-treated, e.g., formed of a synthetic resin, glass, a metal, an animal or a plant, or a ceramic, by bringing a liquid compound in or a compound solution into contact with the surface of the solid workpiece preferably by using a capillary phenomenon, and irradiating the sample with light in this state. The present invention also relates to an adhesion method and a marking method using this surface modification method, and an apparatus for carrying out these methods.There are known a method in which for the purpose of modifying the surface of a fluoroplastic, which is difficult to adhere because of its small affinity for other substances, a fluoroplastic is immersed in a treatment solution comprising liquid ammonia or naphthalene containing metal sodium and tetrahydrofuran to modify the surface, as well as a method of chemically modifying the surface of a polyethylene o...

AI Technical Summary

Benefits of technology

If the solid material to be treated is a fluoroplastic material, a solution having an atom, such as B, Al, Ba, Ga, Li, H, or Ti, whose bonding energy to a fluorine atom is larger than 128 kcal / mol, which is the bonding energy between a carbon atom and a fluorine atom, and a functional group with affinity for an adhesive, such as one selected from --OH, --Cl, --NO.sub.2, --CN, --NH.sub.2, --COOH, --CO, --OCH.sub.3, --OC.sub.2 H.sub.5, --OC.sub.3 H.sub.7, --OC.sub.4 H.sub.9, --CONH, --CH.sub.3, --C.sub.2 H.sub.5, --CH.sub.2, --SO.sub.3 H, --C.sub.3 H.sub.7, --C.sub.4 H.sub.9, and --C.sub.6 H.sub.5, is brought into contact with the surface of the fluoroplastic material, and in this state ultraviolet radiation in an amount sufficient to liberate fluorine from the fluoroplastic material, i.e., at at least a photoenergy corresponding to the bonding energy of 128 kcal / mol is irradiated on the interface between the fluoroplastic material and the solution. Consequently, it is possible to liberate fluorine from the fluoroplastic material and at the same time substitute the fluorine with this functional group, thereby performing surface modification. This surface-modified fluoroplastic material can be easily bonded to a material of the same kind or a different kind via the adhesive.

As discussed earlier, the angle of contact between a substance to be modified and a liquid is large. For this reason, the contact area with the surface of a sample becomes small, and bubbles generated by photo-decomposition further decrease the contact area. As in the present invention, however, by keeping the sample and the glass surface in tight contact with each other and interposing a compound solution between them by using capillarity, an even thin liquid film can be formed on the entire surface of the sample. When ultra-violet radiation is incident from the side of the glass surface, the liquid is locally, optically decomposed, and the surface of the sample is also excited with a fraction of light transmitted through the liquid, bringing about a chemical reaction. Additionally, since the liquid film is thin, all parts of the decomposition product are consumed in the surface treatment, so no excess reaction product which causes generation of bubbles forms. Consequently, no bubbles are generated, making a highly efficient surface treatment possible.

Problems solved by technology

Unfortunately, these conventional chemical modification methods have problems in that, in the case of a fluoroplastic, for example, the surface of a fluoroplastic material turns brown to make the surface layer brittle, resulting in peeling of the adhesive layer.

Consequently, no satisfactory adhesive strength can be obtained.

In addition, although the above conventional methods can modify an entire portion which is immersed, they cannot perform partial modification unless a photoresist is used as a mask.

Also, the treatment reaction is difficult to control, and dangerous chemicals must be used.

However, because of the lack of chemical affinity for an adhesive, a roughened surface formed acts as a stress concentration point, bringing about bonding breakdown.

This makes it impossible to obtain a high bonding strength.

In the method of coating a surfactant, however, the surfactant is readily removed since it does not strongly adhere to a porous body, resulting in difficulty in keeping hydrophilicity.

In the method described in Jpn. Pat. Appln. KOKAI Publication No. 56-63772, deterioration by decomposition of a porous body is brought about if, for example, irradiation is used, and this significantly decreases the mechanical strength.

In addition, the use of a heat treatment, acetal conversion, or esterification poses a problem of a low degree of hydrophilicity, since a portion of the water-soluble polymer is given hydrophobicity.

Also, the method described in Jpn. Pat. Appln. KOKOKU Publication No. 5-77692 is a method of modification of a surface layer; i.e., it is not possible to sufficiently impart hydrophilicity to the bulk of a porous body.

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